1. Field of the Invention
This invention relates to watertight cameras having displaceable strobe devices.
2. Description of the Prior Art
In general, in strobe device built-in cameras, if the distance between the center of the flash lamp and the optical axis of the photographic lens is short when in flash photography, the cameras will have the so-called "red eye" phenomenon, so that in the case of photographing a person, his pupil is photographed as red. To avoid such red eye, it is desirable to increase the distance between the flash lamp and the photographic lens. For example, in 35 mm cameras with next-to-standard wide angle lenses, the distance between these centers is empirically found to be preferably more than about 60 mm.
Further, in application to underwater flash photography, when the water contains many floating particles and, therefore, has diminished transparency, if the flash lamp A lies near the photographic lens B as shown in FIG. 1(a), light from the flash lamp A is reflected from dust particles C to the camera, with the result that such photographs appear as if snow were falling over the entire scene. To avoid this, as shown in FIG. 1(b), the flash lamp A must be put farther away from the photographic lens B so that the reflected light from dust particles C in suspension will not enter the lens. That is to say, even in underwater flash photography, the farther the flash lamp from the photographic lens, the better the result.
Meanwhile, in order to improve portability, it is desirable to minimize the bulk and size of the cameras. In the strobe built-in cameras, the flash lamp is necessarily positioned near the lens. For this reason, in recent years, a retractable strobe has found increasing use in cameras giving an advantage that when the strobe is not in use, the strobe is retracted into the interior of the camera housing to improve the portability, while when it is desired to perform flash photography, the strobe is extracted out of the camera housing to avoid production of the "red eye".
In the prior art of watertight cameras, however, it has been very difficult to assure the watertightness when the strobe is extracted or projected in water. Therefore, to avoid producing the "red eye", the strobe was fixedly mounted within the camera housing. Or otherwise, though the strobe was allowed to remain within the camera, to achieve avoidance of the "red eye", the size of the camera was increased.
Recently though, a watertight camera having a strobe device made pivotally movable between a chamber therefor and a projected position has been proposed in Japanese Laid-Open Utility Model Application No. SHO 58-71727.
This watertight camera allows for assurance of watertightness during the movement of the strobe. But, as shown in FIG. 2(a), because the shaft 23 about which the strobe unit 22 turns lies at the side of the camera body 21, when the strobe unit 22 is in the projected position, the strength against the external pressure is not sufficient. Particularly since the watertight camera is often used under water, a large external force is applied to the strobe unit 22 and there is a high possibility of breaking the connection between the camera body 21 and the strobe unit 22 at the shaft 23.
Another feature of this prior known watertight camera is that all the walls of the chamber 21a for the strobe unit 22 are flat. With the strobe unit 22 snugly accommodated in the chamber, therefore, when water 24 encloses the narrow gap therebetween as shown in FIG. 2(b), the force necessary to pull out the strobe unit 22 is substantially increased by the surface tension of water layer. Particularly after the camera was used in the sea, as the water is evaporated leaving salt crystals behind, the difficulty of pulling out the strobe unit is intensified. Moreover, there is some possibility of heavily eroding the walls of the chamber and the casing of the strobe unit.